Ok, so following your advice i am going to choose gp20, if the bright is good, instead of buying the gp30 (that costs 100 euro more than gp20 one's). If the difference is only 200 lumen between two projector, i surely prefer the first!! :)﻿

You can see my other 15 videos comparing and showing the projector in different conditions to choose what you need. Important thing is that any projector don't make black color itself so if the wall is bright or showing scene is dark there is no matter how lamp in projector is bright you'll just see your wall. ﻿

In this video I don't understand very well what is the result because there isn't a white or grey normal wall...in your opinion, the quality and luminosity are good for watch films on 180", light off ? I haven't decided yet if to buy the gp30 or gp20...﻿